SM-78 Jupiter

The SM-78 Jupiter was a medium-range, ground-launched, liquid-fueled ballistic missile developed and deployed by the United States. It was the first U.S. medium-range missile, and was designed to replace the U.S. Army’s shorter-ranged PGM-11 Redstone missile, although it was later transferred to the U.S. Air Force and lost its mobility. Due to its limited range, the Jupiter was forward based to allied European countries for deterrence against the Soviet Union.

SM-78 Jupiter Development

The Jupiter entered development in 1954 under the leadership of Dr. Werner Von Braun with many of its components constructed by the Chrysler Corporation. From its beginning, the project faced criticism from Air Force leaders who believed that the missile’s range made it a strategic weapon, not a battlefield support weapon, which they considered to be an encroachment on their mission by the Army.

The conflict between the Army and the Air Force grew when the Air Force began developing its IRBM, the Thor. Throughout 1956, the Army and Air Force disagreement made national headlines when officials from both branches began denouncing the other publically.

In order to end the dispute, Secretary of Defense Charles Wilson signed a memorandum in November 1956 stating that the Jupiter would be transferred to the Air Force and the Army would be limited to developing short range and battlefield support weapons with ranges of less than 320 km.1 The Jupiter missile was also considered by the Navy for a sea-launched system, which led to a collaborative development effort between the Army and Navy. The sea-launched missile concept later evolved into the Navy’s Polaris sub launched ballistic missile (SLBM) program.

The Jupiter was first flight tested in 1957 and entered operation service in 1959.

Specifications

The Jupiter missile had a range of 2,400 km (1,491 miles) with the same Mk 3 and 4 reentry vehicles and used the same 1.44 MT W-49 warheads used on the Atlas missile. It featured an inertial navigation system which, though only accurate to 1,800 m CEP, was revolutionary at its time. The missile was 18.39 m long, 2.67 m wide and had a launch weight of 49,885 kg.2 it was roughly the size of most modern intercontinental missiles, it had a significantly shorter range due to its extremely heavy single-stage liquid propellant design.

Service History

The Jupiter was a theater-based system intended for use against strategic targets. While the Jupiter’s navigation system was quite accurate for its time, the missile was ineffective at destroying hardened targets due to its 1.8km CEP. However, the missile was capable of targeting cities, major staging areas, and troop transit points in the event of hostilities. After the missiles were transferred to the Air Force in 1956, the Air Force chose to transition the Jupiter to a fixed-launch missile, as the Army’s mobile variant was dependent on ground vehicles the Air Force did not possess.3

In 1958 and 1959, Jupiters were deployed to Italy and Turkey as a forward strike capability.4 Thirty missiles were deployed to Italy and fifteen in Turkey. An additional fifteen missiles were scheduled for deployment to Turkey, but these plans were later canceled.5 The missiles in Italy provided a direct nuclear threat against the Soviet Union, its satellite states and armed forces, and played a reassurance role for U.S. European allies. Meanwhile, the missiles based in Turkey were capable of threatening Moscow and other major Russian cities.

During the Cuban Missile Crisis in late 1962, the Kennedy Administration quietly negotiated the removal of Soviet SS-4 and SS-5 missiles from Cuba by removing the Jupiter missiles based in Italy and Turkey. All Jupiter missiles were retired two years later in 1964.6

Modified Jupiter missiles were used as the first stage boosters of the Juno satellite launch vehicles. Jupiter missiles were used to put the U.S. Explorer satellites into orbit.7

Missile Threat brings together a wide range of information and analyses relating to the proliferation of cruise and ballistic missiles around the world and the air and missile defense systems designed to defeat them. Missile Threat is a product of the Missile Defense Project at the Center for Strategic and International Studies.

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